docs: def hx2dp(string):
      """
      Convert a string representing a double precision number in a
      base 16 scientific notation into its equivalent double
      precision number.
  
      http://naif.jpl.nasa.gov/pub/naif/toolkit_docs/C/cspice/hx2dp_c.html
  
      :param string: Hex form string to convert to double precision.
      :type string: str
      :return: Double precision value to be returned, Or Error Message.
      :rtype: float or str
      """
      string = stypes.stringToCharP(string)
      lenout = ctypes.c_int(80)
      errmsg = stypes.stringToCharP(lenout)
      number = ctypes.c_double()
      error = ctypes.c_int()
      libspice.hx2dp_c(string, lenout, ctypes.byref(number), ctypes.byref(error),
                       errmsg)
      if not error.value:
          return number.value
      else:
          return stypes.toPythonString(errmsg)